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Description of key information

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records
Reference
Endpoint:
skin sensitisation
Remarks:
in vivo
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP and guideline study
Qualifier:
according to
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
yes
Remarks:
modification refer to measurement of cell proliferation by cell counting instead of radioactive labeling; in addition the acute inflammatory skin reaction is determined to discriminate specific from non-specific activation of immune competent cells in the
Qualifier:
according to
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
yes
Remarks:
modification refer to measurement of cell proliferation by cell counting instead of radioactive labeling; in addition the acute inflammatory skin reaction is determined to discriminate specific from non-specific activation of immune competent in the drai
GLP compliance:
yes
Type of study:
mouse local lymph node assay (LLNA)
Species:
mouse
Strain:
NMRI
Sex:
female
Vehicle:
acetone/olive oil (4:1 v/v)
Concentration:
0, 2%, 10% 50%
No. of animals per dose:
6 per dose group
Parameter:
SI
Remarks on result:
other: neither a non-specific (irritant nor a specific immunostimulating (sensitzing) potential of the test item was revealed; cell count index: vehicle control: 1.00, 2%: 1.17, 10%: 1.16, 50%: 1.22

Groups of female NMRI mice were treated with vehicle, 2%, 10% or 50% test substance in AOO.

The NMRI mice treated with the test substance 6,6’-di-tert-butyl-2,2’-methylendi-p-cresol did not show an increase in the stimulation indices for cell counts or for weights of the draining lymph nodes. The "positive level" which is 1.4 for the cell count index was not reached or exceeded in any dose group (cell count index: 1.0, 1.17, 1.16, 1.22 at 0, 2%, 10% or 50% test substance solution, respectively). The “positive level” of ear swelling, which is 2x 10-2 mm increase, i.e. about 10% of the control values, was not reached or exceeded in any treatment group. In addition, no substance specific effects were determined for ear weights.

no treatment-related effcts on body weights were noted.

Based on the findings of this study, the author suggested that neither a non-specific (irritant) nor a specific immune stimulating (sensitizing) potential of the test substance was indicated.

Table: Direct LLNA (NMRI mice, 6 animals/group) lymph node weight index and cell count index (index mean ± SD in %)

 Dose (%)  Weight index (index mean ± SD in %)  Cell count index (index of mean ± in %)
 0  1.00 ± 13.89  1.00 ±16 .46
 2  1.11 ± 16.92  1.17 ± 17.57
 10  1.09 ± 11.56  1.16 ± 13.12
 50  1.08 ± 14.16  1.22 ± 8.07

Table: Ear swelling (NMRI mice, female, 6 animals/group, in 0.01 mm)

 Dose (%)  day 1 (mean ± SD in %)  day 4 (mean ± SD in %)  Index day 4
 17.42 ± 2.96  17.67 ± 2.79  1.00
 2  17.25 ± 2.62  18.42 ± 4.89  1.04
 10  17.58 ± 3.80  18.58 ± 8.10  1.05
 50  17.67 ± 2.79  18.33 ± 3.55  1.04
       

Table Ear weight (NMRI mice, female, 6 animals/group, in mg per 8 mm diameter punch)

 Dose (%)  day 4 (mean ± SD in %)  Index day 4
 0  12.20 ± 7.11  1.00
 2  12.83 ± 8.30  1.05
10 12.90 ± 7.62  1.06
 50  12.63 ± 9.88  1.04
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

Non-Human information

The skin sensitizing potential of 6,6’-di-tert-butyl-2,2’-methylendi-p-cresol (DBMC) were evaluated in a modified Local Lymph node Assay (LLNA), done under GLP and in accordance with current guidelines (OECD TG 429, OECD TG 406) (Bayer Schering Pharma AG 2010). Female NMRI mice (6 animal/ test substance group and 6 control animals) were evaluated to determine if there is any specific (sensitizing) or non-specific (irritant) stimulating potential of the test substance. The test substance was formulated in acetone/olive oil (4:1) and was administered epicutaneously onto the dorsal part of both ears (25 µl/ear) at concentration of 0, 2%, 10% and 50%. This treatment was repeated on three consecutive days. The animals were scarified one day after the last application and the lymphatic organs (the auricular lymph nodes) were removed and transferred into physiological saline (PBS). The weights of lymph nodes were determined; afterward the lymph nodes were crushed through a sieve and the cell count determined. The stimulation index was calculated by dividing the absolute number of weight or cell counts of the substance treated lymph nodes by the vehicle treated ones. Before the first treatment and before sacrifice the thickness of both auricles of the animals was measured. The ear weight of the sacrificed animals was measured using a punch to take of a piece of every ear with a diameter of 8 mm. The weights were determined on a semiautomatic balance The NMRI mice treated with the test substance 6,6’-di-tert-butyl-2,2’-methylendi-p-cresol did not show an increase in the stimulation indices for cell counts or for weights of the draining lymph nodes. The "positive level" which is 1.4 for the cell count index was not reached or exceeded in any dose group (cell count index: 1.0, 1.17, 1.16, 1.22 at 0, 2%, 10% or 50% test substance solution, respectively). The “positive level” of ear swelling, which is 2x 10-2 mm increase, i.e. about 10% of the control values, was not reached or exceeded in any treatment group. In addition, no substance specific effects were determined for ear weights. Based on the findings of this study, the author suggested that neither a non-specific (irritant) nor a specific immune stimulating (sensitizing) potential of the test substance was indicated.

Human information

In several patch-tests with contact dermatitis patients no or even few positive skin reactions were seen when patch-tested with 6,6’-di-tert-butyl-2,2’-methylendi-p-cresol (DBMC) (Wilson 1960, van Dijk 1968, Kanto 1985 and 1999).


Short description of key information:
The skin sensitizing potential of the test substance 6,6’-di-tert-butyl-2,2’-methylendi-p-cresol (DBMC) was evaluated in a modified Local Lymph node assay (Bayer Scherig Pharma AG 2010). Neither a non-specific (irritant) nor a specific immune stimulating (sensitizing) potential of the test substance was indicated in treated female NMRI mice.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available
Additional information:

No classification is required according to the classification criteria 67/548/EWG and regulation no. 1272/2008 (GHS).


Short description of key information:
No experimental data available; since no skin sensitization was observed in comprehensive studies, no respiratory sensitization is expected.

Justification for classification or non-classification